JP7521318B2 - Thrust generating device - Google Patents

Description

The present invention relates to a thrust generating device.

A technology for electrically varying the pitch, which is the mounting angle of a propeller (rotor blade) relative to the rotating shaft, without using hydraulics, is disclosed, for example, in Patent Document 1. In this technology, the rotating main shaft is formed to be hollow, and an operating rod is arranged concentrically within this rotating main shaft so that it can move only in the axial direction, and an arm fixed to the lower end of the operating rod is connected to each support shaft of the blade via a link and lever mechanism. Then, by moving the operating rod back and forth in the axial direction, the mounting angle of each blade is changed via the link and lever mechanism.

Japanese Patent Application Publication No. 5-87037

In the case of flying objects such as multicopters, airplanes, rotorcraft, and flying automobiles, it becomes difficult to ensure stability when the size increases. Therefore, it is necessary to reduce the weight of the flying object. In order to reduce the weight of the flying object, it is desirable for the thrust generating device that provides thrust to the flying object to be small and lightweight.
SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a thrust generating device that can be made smaller and lighter.

In order to solve the above problem, a thrust generating device according to one aspect of the present invention includes a thrust generating motor that generates thrust by rotating a plurality of rotors, a pitch angle changing motor that changes the pitch angle of the rotors, a rotation transmitting unit connected to the pitch angle changing motor, a linear shaft, and a first motion converting mechanism, the first motion converting mechanism being connectable to the rotation transmitting unit and the linear shaft and converting rotation of the rotation transmitting unit into linear motion of the linear shaft, and a third motion converting mechanism that converts the linear motion of the linear shaft into rotational motion to change the pitch angle of the rotors. and a second motion conversion unit, the second motion conversion unit comprising a hub rotated by the thrust generating motor, a plurality of grips attached to the hub and each supporting one of the rotors, a second motion conversion mechanism that converts the linear motion of the linear shaft into rotational motion of the plurality of grips, and a plurality of radial bearings that rotatably support inner ends of the grips, respectively, and the hub has an integrally formed non-split type case that houses the inner ends of the plurality of grips, the second motion conversion mechanism, and the plurality of radial bearings.
With this configuration, the thrust generating device can be made smaller. Also, since the inner ends of the multiple grips, the second motion converting mechanism, and the multiple radial bearings are housed in an integrally formed non-split case, the strength can be increased and the weight can be reduced compared to when a split case is used.

In addition, in the above-mentioned thrust generating device, the second motion conversion unit may further include a plurality of tubes into which the inner ends of the grips are respectively inserted and which are respectively inserted into the radial bearings, each tube being divisible along a plane including the longitudinal axis of the grip, and the non-split case may have a plurality of openings into which the inner ends of the grips can be inserted when the outer ends of the grips are positioned outside the non-split case.
In this case, the inner end of the grip is inserted through an opening of the non-split case and disposed inside the non-split case. Inside the non-split case, the radial bearing is disposed around the inner end of the grip so as to rotatably support the grip. Specifically, the inner end of the grip is inserted into a tube, and the tube is inserted into the radial bearing. Each tube can be divided at a plane including the longitudinal axis of the grip as a boundary, and can be easily disposed around the inner end of the grip and easily inserted into the radial bearing in a combined state. Therefore, even if the case is a non-split case that cannot be divided, it is possible to easily dispose the radial bearing around the inner end of the grip inside the case.

Furthermore, in the above-mentioned thrust generating device, the non-split case may have a plurality of hollow portions in which the radial bearings are arranged, the inner diameter of the hollow portions may be larger than the inner diameter of the openings, and no holes may be formed in the non-split case at positions opposite the plurality of openings.
For example, when forming a hollow portion with a diameter larger than that of the opening that holds the grip by cutting out the opening, a machining hole is provided at a position opposite the opening, and a cutting tool is inserted through the machining hole to form the hollow portion. However, when a machining hole is provided, it is necessary to make the case thicker to ensure strength, which causes a problem of increased weight. By adopting a structure that does not provide a machining hole as described above, it is possible to achieve a reduction in weight.

Furthermore, a manufacturing method according to one aspect of the present invention is a manufacturing method for the non-split case of any of the thrust generating devices described above, and includes the steps of preparing a base material for the non-split case and forming the non-split case by machining out the base material.
This makes it possible to manufacture a case that is both strong and lightweight. In addition, there is no difference in hardness, as occurs in cases where the case is manufactured by press working, and the case can be made of a uniform material.

In addition, in the above manufacturing method, the step of forming the non-split case may include a step of forming an accommodating portion that penetrates a pair of opposing surfaces of the base material and accommodates the second motion conversion mechanism, and a step of applying a cutting tool to openings at both axial ends of the accommodating portion obliquely with respect to the axial direction of the accommodating portion to form a hollow portion in which the multiple radial bearings are arranged, outside the accommodating portion and connected to the accommodating portion.
In this case, it is possible to eliminate the need for a hole for forming a hollow portion with a diameter larger than the opening that holds the grip, on the inside of the opening, and therefore it is possible to manufacture a case that is both strong and lightweight.

According to one aspect of the present invention, it is possible to achieve compactness and weight reduction.

FIG. 1 is a perspective view showing a thrust generating device according to an embodiment to which rotors are attached. FIG. 2 is a side view showing a thrust generating device according to an embodiment having rotors attached thereto. FIG. 3 is a side view showing a thrust generating device according to an embodiment having rotors attached thereto. FIG. 4 is an exploded perspective view of the thrust generating device according to the embodiment. FIG. 5 is an exploded perspective view of the thrust generating device according to the embodiment as viewed from another direction. FIG. 6 is a plan view of the thrust generating device according to the embodiment. 7 is a cross-sectional view taken along line VII-VII of FIG. FIG. 8 is a plan view of the rotation transmission unit and the rotary-to-linear conversion unit of the thrust generating device according to the embodiment. FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. FIG. 10 is a cross-sectional view taken along line X-X of FIG. FIG. 11 is a perspective view of a rotation transmission unit and a rotary-to-linear conversion unit of the thrust generating device according to the embodiment. FIG. 12 is a perspective view of the linear motion transmission shaft and the ball screw nut of the rotary-linear motion conversion unit. FIG. 13 is a perspective view showing a linear body of the linear motion-rotation converting unit of the thrust generating device according to the embodiment, and the position of the linear body corresponds to the pitch angle of the rotor in FIG. FIG. 14 is a perspective view showing a linear moving body, the position of which corresponds to the pitch angle of the rotor blades in FIG. FIG. 15 is an exploded perspective view of a hub of the thrust generating device according to the embodiment. FIG. 16 is a bottom view of the hub case. 17 is a cross-sectional view taken along line XVII-XVII of FIG. 16. FIG. FIG. 18 is an enlarged cross-sectional view of a portion of the hub. FIG. 19 is a cross-sectional view of the grip and its vicinity of the thrust generating device according to the embodiment. FIG. 20 is an exploded perspective view of the components shown in FIG. FIG. 21 is a front view of the components shown in FIG. 19 assembled. FIG. 22 is a cross-sectional view of another type of grip and its vicinity in the thrust generating device according to the embodiment. FIG. 23 is an exploded perspective view of the components shown in FIG. FIG. 24 is a diagram illustrating a method for manufacturing the case.

The following describes in detail the embodiments of the present invention with reference to the accompanying drawings. The following embodiments do not limit the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the configuration of the present invention. The configuration of the embodiments may be modified or changed as appropriate depending on the specifications of the device to which the present invention is applied and various conditions (conditions of use, environment of use, etc.). The technical scope of the present invention is determined by the claims and is not limited by the individual embodiments below. The drawings are not necessarily drawn to scale, and some features may be exaggerated or omitted.

In the following explanation, we will use an example in which the rotor driven by the thrust generating device has three blades, but the number of blades driven by the thrust generating device is not necessarily limited to three, and may be N (N is a positive integer).

Figure 1 is a perspective view showing a thrust generating device according to an embodiment in which rotors are attached. Figures 2 and 3 are side views showing thrust generating devices according to an embodiment in which rotors are attached, with the rotors having different pitch angles.

As shown in Figures 1 to 3, the thrust generating device 1 rotates a rotor or propeller R having multiple rotors H1 to H3. The propeller R is disposed directly below the thrust generating device 1. The propeller R has grips P1 to P3, which support the rotors H1 to H3 so that they extend radially in the horizontal direction from the thrust generating device 1.

The thrust generating device 1 is attached to the airframe of the flying object via the upper attachment part 1A. The flying object to which the thrust generating device 1 is attached is, for example, a flying object or vehicle such as a motor-driven multicopter, an airplane, a rotorcraft, or an automobile equipped with a flying function. Although not shown, a plurality of thrust generating devices 1 each having a propeller R attached thereto may be attached to the airframe of the flying object.

The thrust generating device 1 comprises a thrust generating motor 2, a pitch angle changing motor 5A, and a motion transmission unit 6. The thrust generating motor 2 rotates the propeller R to generate thrust to be applied to the flying object. The pitch angle changing motor 5A changes the pitch angles θ1 to θ3 of the rotors H1 to H3. By changing the pitch angles θ1 to θ3 of the rotors H1 to H3, it is possible to change the thrust to be applied to the flying object. The motion transmission unit 6 transmits the rotational motion of the pitch angle changing motor 5A to the rotors H1 to H3.

Figures 4 and 5 are exploded perspective views of the thrust generating device 1. Figure 6 is a plan view of the thrust generating device 1, and Figure 7 is a cross-sectional view taken along line VII-VII in Figure 6. As shown in Figures 4 to 7, the thrust generating motor 2 comprises a stator 2A, a rotor 2B, and a frame 2C. The rotor 2B comprises a rotor shaft 4 and hollow portions 3A and 3C on the radially inner side.

The stator 2A is composed of an electromagnetic steel plate and windings, and is located outside the rotor 2B. The stator 2A is fixed to the annular portion of the frame 2C, which is arranged outside the stator 2A. The mounting portion 1A of the thrust generating device 1 can be provided in the center of the frame 2C. The mounting portion 1A has an opening 1B, into which the motion transmission unit 6 is inserted. The mounting portion 1A is connected to the annular portion via a plurality of spokes 1C extending radially. The frame 2C is formed with an inner cylindrical portion 1D, which rotatably supports the rotor shaft 4 via a bearing U1. The frame 2C, including the annular portion, the mounting portion 1A, the spokes 1C, and the inner cylindrical portion 1D, can be formed, for example, by cutting an alloy such as duralumin.

The rotor 2B of the thrust generating motor 2 is connected to the rotor shaft 4 via multiple spokes 2D extending radially. The rotor 2B rotates together with the rotor shaft 4 about the central axis S0 (see Figures 2 and 3). The rotor 2B and the rotor shaft 4 are rotatably supported by the frame 2C via the bearing U1.

The hollow portion 3A is provided between the rotor 2B and the rotor shaft 4. The pitch angle change motor 5A is disposed in the hollow portion 3A. The pitch angle change motor 5A is fixed to the frame 2C.

The hollow portion 3C is the central hole of the rotor shaft 4 and extends along the axial direction of the rotor shaft 4. A part of the motion transmission unit 6 is inserted into the hollow portion 3C.

A hollow cylindrical extension 9 is fixed to the lower end surface of the rotor shaft 4 of the thrust generating motor 2, and the extension 9 is fixed to the hub 10 of the rotor R. The hub 10 is therefore supported by the frame 2C in a state in which it can rotate around the central axis S0. Grips P1-P3 that support the rotor blades H1-H3 are attached to the hub 10. In this way, the thrust generating motor 2 rotates the propeller R having the rotor blades H1-H3. That is, when the thrust generating motor 2 operates and the rotor 2B rotates, the rotor shaft 4 rotates, and the rotor blades H1-H3 rotate around the central axis S0. As the rotor blades H1-H3 rotate, thrust is generated and applied to the flying object.

The extension 9 is a spacer that maintains a gap between the thrust generating motor 2 and the rotors H1 to H3 in the axial direction of the thrust generating device 1, and prevents the rotors H1 to H3 from colliding with the thrust generating motor 2. The material of the extension 9 is, for example, duralumin.

The pitch angle changing motor 5A, which changes the pitch angle of the rotor blades H1 to H3, is fixed to the frame 2C of the thrust generating motor 2 and is disposed inside the thrust generating motor 2, specifically in the hollow portion 3A. The rotation shaft of the pitch angle changing motor 5A extends vertically, just like the rotor shaft 4 of the thrust generating motor 2. In other words, the rotation shaft of the pitch angle changing motor 5A and the rotor shaft 4 are different parallel shafts.

Next, we will explain the motion transmission unit 6 that transmits the rotational motion of the pitch angle change motor 5A to the rotors H1 to H3. The motion transmission unit 6 includes a rotation transmission section 6A, a rotary-to-linear motion conversion section 7, and a linear-to-rotary motion conversion section 8.

The rotation transmission unit 6A transmits the rotation of the rotating shaft of the pitch angle change motor 5A to the ball screw shaft 7F of the rotary-linear conversion unit 7. The ball screw shaft 7F extends vertically along the central axis S0 of the thrust generating device 1 and is disposed within the hollow portion 3C, which is the central hole of the rotor shaft 4. Therefore, the rotation transmission unit 6A transmits the rotational motion of the pitch angle change motor 5A to the shaft on the central axis S0. Each rotation transmission unit has a rotating member that rotates in conjunction with the rotation of the rotating shaft of the pitch angle change motor. The rotation transmission unit 6A is fixed to the frame 2C.

The rotary-linear converter (first motion converter) 7 has a linear transmission shaft (linear shaft) 7D that extends vertically along the central axis S0 of the thrust generating device 1, and a motion conversion mechanism that converts the rotation of the rotary transmission unit 6A into linear motion of the linear transmission shaft 7D. The motion conversion mechanism (first motion conversion mechanism) of the rotary-linear converter 7 is connected to the rotary transmission unit 6A and the linear transmission shaft 7D. This motion conversion mechanism has a ball screw shaft 7F that is coaxially arranged above the linear transmission shaft 7D. The upper part of the rotary-linear converter 7 is housed within the thrust generating motor 2, but the lower part of the rotary-linear converter 7 protrudes downward from the thrust generating motor 2. The rotary-linear converter 7 is fixed to the frame 2C.

The linear motion-rotation conversion unit (second motion conversion unit) 8 converts the linear motion of the linear motion transmission shaft 7D of the rotary-linear motion conversion unit 7 into rotational motion to change the pitch angle of the rotors H1 to H3. The linear motion-rotation conversion unit 8 is located below the thrust generating motor 2.

The pitch angle change motor 5A, the rotation transmission unit 6A, and the rotary-linear conversion unit 7 are fixed to the frame 2C of the thrust generating motor 2. Therefore, even if the rotor shaft 4 rotates, the pitch angle change motor 5A, the rotation transmission unit 6A, and the rotary-linear conversion unit 7 do not rotate around the rotor shaft 4. On the other hand, the linear-rotation conversion unit 8 is supported by the rotor shaft 4. Therefore, the linear-rotation conversion unit 8 rotates around the rotor shaft 4 as the rotor shaft 4 rotates.

As shown in Figures 8 to 11, gear G1 is fixed to the upper end of the ball screw shaft 7F of the rotary-linear conversion unit 7. The rotation transmission unit 6A has gears G2 and G3, with gear G3 fixed to the rotating shaft of the pitch angle change motor 5A and gear G2 meshing with gears G3 and G1. Therefore, in the rotation transmission unit 6A, gears G3 and G2 can transmit the rotational motion of the pitch angle change motor 5A to the ball screw shaft 7F fixed to gear G1. The material of the gears G1 to G3 is, for example, carbon steel.

The rotary-linear converter 7 is supported by a support member F1. As shown in Figures 4, 6 and 7, the support member F1 is disposed in an opening 1B of the mounting portion 1A of the frame 2C of the thrust generating motor 2. The support member F1 is supported on the frame 2C by, for example, four bolts J1 (see Figures 8 to 11). The bolts J1 can be disposed, for example, at the four corners of the support member F1. A support member F3 is disposed in the hollow portion 3A of the thrust generating motor 2. The support member F3 is also supported on the frame 2C by bolts J3 (see Figures 8, 9 and 11). The pitch angle changing motor 5A is fixed to the support member F3 in the hollow portion 3A by bolts J4 (see Figures 8 to 11).

As shown in Figures 8 to 11, support member F2 is supported by bolt J2 on support member F1, and support member F1 and support member F2 rotatably support gear G2 of rotation transmission unit 6A. Support members F1 to F3 are made of a material such as an aluminum alloy.

In this embodiment, in the rotation transmission unit 6A, gears transmit the rotational motion of the pitch angle change motor 5A to the ball screw shaft 7F of the rotary-linear motion conversion unit 7. The rotation transmission unit may have a belt-pulley mechanism or a chain-sprocket. Specifically, a pulley may be fixed to the ball screw shaft 7F, and a belt may be wound around this pulley and a pulley fixed to the rotating shaft of the pitch angle change motor 5A. A timing belt may be used as the belt. A sprocket may be fixed to the ball screw shaft 7F, and a chain may be wound around this sprocket and a sprocket fixed to the rotating shaft of the pitch angle change motor 5A.

In this embodiment, the rotary-linear conversion unit 7 uses a ball screw as a motion conversion mechanism to convert the rotary motion of the ball screw shaft 7F into linear motion of the linear transmission shaft 7D. The motion conversion mechanism includes a ball screw shaft 7F, a ball screw nut 7G, and a pair of linear guides 7E. However, a sliding screw or other feed screw may be used instead of the ball screw. In this embodiment, by using a ball screw as the motion conversion mechanism of the rotary-linear conversion unit 7, the drive torque can be reduced compared to when a sliding screw is used, and power consumption of the pitch angle change motor 5A can be reduced.

The ball screw shaft 7F extends vertically. As shown in FIG. 7, the ball screw shaft 7F is rotatably supported by a bearing U2 fixed to the cylindrical portion F1a of the support member F1, and rotates about the longitudinal axis of the ball screw shaft 7F as the gear G1 rotates.

As shown in Figures 9 and 10, the ball screw nut 7G is engaged with the ball screw shaft 7F. The ball screw nut 7G also extends vertically and is fixed to a linear motion transmission shaft 7D that extends vertically and is located below the ball screw nut 7G.

As shown in Figures 9 to 11, the ball screw nut 7G and the linear transmission shaft 7D are sandwiched between linear guides 7E, which are a pair of parallel long plate walls protruding from the cylindrical portion F1a of the support member F1, and are restricted from rotating by the pair of linear guides 7E. As the ball screw shaft 7F rotates, the ball screw nut 7G and the linear transmission shaft 7D move linearly in the vertical direction along the axial direction of the ball screw shaft 7F. The linear guides 7E allow the linear motion of the ball screw nut 7G and the linear transmission shaft 7D. In other words, the linear guides 7E guide the ball screw nut 7G and the linear transmission shaft 7D to move linearly. Therefore, when the ball screw shaft 7F rotates together with the gear G1, the ball screw nut 7G and the linear transmission shaft 7D move linearly in the vertical direction, guided by the linear guides 7E. The linear guides 7E can be provided integrally with the support member F1.

As shown in Figures 9 and 10, a vertically extending cavity is formed at the top of the linear motion transmission shaft 7D, and a ball screw nut 7G meshed with the ball screw shaft 7F is inserted into this cavity.

As shown in Figures 10 and 11, two guided flat surfaces 7C are formed on the outer peripheral surface of the upper part of the linear motion transmission shaft 7D. The two guided flat surfaces 7C are parallel to each other. On the other hand, the two linear motion guide parts 7E each have a guide flat surface 7E1, and these guide flat surfaces 7E1 are parallel to each other. The two guided flat surfaces 7C each face the guide flat surfaces 7E1 of the two linear motion guide parts 7E. However, the guided flat surfaces 7C do not contact the guide flat surfaces 7E1, and a small clearance is provided between the guided flat surfaces 7C and the guide flat surfaces 7E1.

As shown in Figures 10 and 12, a recess is formed in each of the guided flat surfaces 7C, and a sliding member 7H made of a low-friction material, such as fluororesin, is fitted into the recess. A part of the sliding member 7H protrudes from the recess and slidably contacts the guide flat surface 7E1 of the linear guide part 7E. Therefore, when the ball screw nut 7G and the linear transmission shaft 7D move linearly in the vertical direction, the sliding member 7H reduces friction with the linear guide part 7E. The sliding member 7H may be fixed to the recess with an adhesive or the like. To further reduce friction, a lubricant such as grease may be coated on the clearance between the guided flat surface 7C and the guide flat surface 7E1.

As shown in Figures 9 to 12, a flange 7A is formed at the upper end of the ball screw nut 7G, and a flange 7B is also formed at the upper end of the linear motion transmission shaft 7D. The flanges 7A and 7B are shaped like a cylinder cut by two parallel planes, with the flange 7A having two arc-shaped protruding portions 7A1 and two flat portions 7A2, and the flange 7B having two arc-shaped protruding portions 7B1 and two flat portions 7B2.

The arc-shaped protruding portions 7A1 and 7B1 of the flanges 7A and 7B are exposed between the pair of linear guides 7E. The protruding portions 7A1 and 7B1 of the flanges 7A and 7B are fixed by the bolt J5, and therefore the linear transmission shaft 7D is fixed to the ball screw nut 7G.

On the other hand, as shown in FIG. 10, the flat portions 7A2 and 7B2 of the flanges 7A and 7B face the guide flat surfaces 7E1 of the two linear guide parts 7E, respectively. The flat portion 7A2 of the flange 7A does not contact the guide flat surface 7E1 of the linear guide part 7E. The flat portion 7B2 of the flange 7B is part of the guided flat surface 7C, and the sliding member 7H is fitted into the recess formed therein. In this way, by providing the flat portions 7A2 and 7B2 on the flanges 7A and 7B, the outer diameter of the pair of linear guide parts 7E can be reduced, and the rotary-linear conversion part 7 can be housed within the rotor shaft 4 while suppressing an increase in the diameter of the rotor shaft 4. Therefore, the thrust generating device 1 can be further reduced in size and weight.

As shown in FIG. 7, most of the rotary-linear converter 7, including the upper part of the linear transmission shaft 7D, is disposed inside the thrust generating motor 2, while the lower part of the linear transmission shaft 7D passes through the internal space of the extension 9, which is a hollow cylinder, and further reaches the inside of the hub 10 of the propeller R.

The lower part of the linear motion transmission shaft 7D is connected to a linear motion rotation conversion unit 8 that converts the linear motion of the rotary-linear motion conversion unit 7 into rotational motion in order to change the pitch angle of the rotors H1 to H3. In this embodiment, the linear motion rotation conversion unit 8 uses a rack and pinion as a motion conversion mechanism (second motion conversion mechanism) to convert the linear motion of the linear motion transmission shaft 7D of the rotary-linear motion conversion unit 7 into rotational motion.

As shown in Figures 4 and 5, the linear motion rotation conversion unit 8 includes a linear body 11, racks A1 to A3, a case 21, support shafts M1 to M3, bearings E1 to E3, shaft adapters D1 to D3, and pinions B1 to B3.

The linear body 11 has a regular triangular prism shape with a cavity formed in its center. As shown in FIG. 7, the lower end of the linear transmission shaft 7D is fitted into the inner ring of the bearing U3, and the outer ring of the bearing U3 is fitted into the cavity of the linear body 11. Therefore, the linear body 11 can rotate around the linear transmission shaft 7D and moves linearly in the vertical direction together with the linear transmission shaft 7D. For example, a double row angular ball bearing can be used as the bearing U3.

The racks A1 to A3 are fixed to three corners of the linear motion body 11 and move linearly together with the linear motion body 11. The racks A1 to A3 are meshed with the pinions B1 to B3, respectively, and the pinions B1 to B3 are caused to rotate simultaneously with the linear motion of the linear motion body 11 and the racks A1 to A3.

The support shafts M1 to M3 are arranged on the extensions of the grips P1 to P3 that support the rotors H1 to H3 of the propeller R. That is, the support shafts M1 to M3 support the grips P1 to P3 so as to extend horizontally radially from the thrust generating device 1. The grip P1 and the support shaft M1 can be provided integrally, the grip P2 and the support shaft M2 can be provided integrally, and the grip P3 and the support shaft M3 can be provided integrally. The material of the grips P1 to P3 and the support shafts M1 to M3 is, for example, duralumin. However, to increase the durability of the grips P1 to P3 and the support shafts M1 to M3, the material of the grips P1 to P3 and the support shafts M1 to M3 can be, for example, titanium.

The support shafts M1 to M3 are supported by bearings E1 to E3 fixed to the case 21 so that they can rotate around their own axes. For example, radial bearings, preferably double row angular contact ball bearings, can be used as E1 to E3.

The pinions B1 to B3 are fixed to the tips of the support shafts M1 to M3, respectively. Therefore, when the pinions B1 to B3 rotate in accordance with the linear motion of the linear body 11 and the racks A1 to A3, the support shafts M1 to M3 also rotate together with the grips P1 to P3. The material of the pinions B1 to B3 and the racks A1 to A3 is, for example, chrome molybdenum steel.

The case 21 is a part of the hub 10 of the propeller R. The case 21 houses the linear body 11, racks A1 to A3, support shafts M1 to M3, bearings E1 to E3, shaft adapters D1 to D3, and pinions B1 to B3. Therefore, the case 21 can also be considered as the case of the linear motion rotation conversion unit 8.

The upper part of the case 21 is fixed to the lower end of the extension 9, which is a hollow cylinder, and the upper end of the extension 9 is fixed to the rotor shaft 4 of the thrust generating motor 2. Therefore, the case 21 rotates around the axis of the thrust generating device 1 together with the rotor 2B and the rotor shaft 4.

The bearings E1 to E3 fixed to the case 21 can support the support shafts M1 to M3 against the centrifugal force acting on the rotors H1 to H3 when the thrust generating device 1 rotates around its axis.

As shown particularly in Figures 18 to 20, the shaft adapters D1 to D3 are arranged outside the support shafts M1 to M3 and inside the bearings E1 to E3, respectively, and are supported by the support shafts M1 to M3. The inner circumferential surface of each shaft adapter D1 to D3 is formed to fit the outer circumferential surface of the support shafts M1 to M3, which vary in diameter, and the outer circumferential surface of each shaft adapter D1 to D3 is formed to fit the inner circumferential surface of the cylindrical bearings E1 to E3. The shaft adapters D1 to D3 allow the bearings E1 to E3 to support the support shafts M1 to M3 while accommodating changes in the diameter of each support shaft M1 to M3. The case 21 and the shaft adapters D1 to D3 are made of a material such as duralumin.

The linear body 11, racks A1-A3, support shafts M1-M3, bearings E1-E3, shaft adapters D1-D3, and pinions B1-B3 housed in the case 21 rotate together with the case 21 around the axis of the thrust generator 1. As described above, the linear body 11 is fixed to the outer ring of the bearing U3, and can rotate around the axis of the thrust generator 1 independently of the linear transmission shaft 7D fixed to the inner ring of the bearing U3. As shown in FIG. 7, the inner ring of the bearing U3 can be fixed to the lower end of the linear transmission shaft 7D by, for example, a nut 15, and the outer ring of the bearing U3 can be fixed to the linear body 11 by, for example, a C-shaped retaining ring 16.

Figure 13 shows the position of the linear body 11 corresponding to the pitch angle of the rotor blade in Figure 2, and Figure 14 shows the position of the linear body 11 corresponding to the pitch angle of the rotor blade in Figure 3. As shown in Figures 13 and 14, the linear motion rotation conversion unit 8 includes a base 13, lift guides T1-T3, and nuts S1-S3 to limit the range of movement of the linear body 11 in the linear direction. The base 13 is an equilateral triangular plate with the same outline as the linear body 11, and a through opening 14 is formed in the center of the base 13 through which the lower end of the linear transmission shaft 7D can pass. The base 13 supports parallel lift guides T1-T3, which are rods extending vertically. The lift guides T1-T3 can be provided integrally with the base 13.

The linear body 11, which has the shape of a regular triangular prism, has three side faces Z1 to Z3. Racks A1 to A3 are fixed to the side faces Z1 to Z3, respectively. A cavity 12 is formed in the center of the linear body 11, and a bearing U3 (see Figure 7) is disposed in the cavity 12.

Openings V1 to V3 are formed at the three corners of the linear body 11. Lift guides T1 to T3 fixed to the base 13 are inserted into the openings V1 to V3, respectively. Nuts S1 to S3 are attached to the lower ends of the lift guides T1 to T3, respectively.

Fig. 15 is an exploded perspective view of the hub 10. Fig. 16 is a bottom view of the case 21 of the hub 10. Fig. 17 is a cross-sectional view taken along line XVII-XVII in Fig. 16. The hub 10 comprises the case 21, the outer cover 22,
and an inner lid 23. The case 21 includes a storage portion 21A, an opening 21B, an opening 21C, hollow portions Q1 to Q3, and openings K1 to K3 (see FIGS. 4 and 5).

The accommodation section 21A is formed in the center of the case 21. The accommodation section 21A accommodates the linear motion body 11 to which the racks A1 to A3 shown in FIG. 13 are attached together with the base 13. The accommodation section 21A also accommodates the pinions B1 to B3 (see FIG. 4) that mesh with the racks A1 to A3. The accommodation section 21A is, for example, a hollow section or a recessed section provided in the case 21. The planar shape of the accommodation section 21A corresponds to the planar shape of the base 13 and can be a substantially equilateral triangle.
The opening 21B is formed in one surface (lower surface) of a pair of opposing surfaces (upper and lower surfaces) of the case 21, and communicates with the storage section 21A. The opening 21B is formed in order to place the linear body 11 and the base 13 to which the racks A1 to A3 are attached in the storage section 21A through the opening 21B.

Opening 21C is formed on the other (upper) of a pair of opposing surfaces (upper and lower surfaces) of case 21, and communicates with storage section 21A. Opening 21C is a hole through which the lower end of the linear motion transmission shaft 7D described above is inserted. The planar shape of opening 21C can be, for example, circular.

Hollow sections Q1 to Q3 are arranged at angular intervals of 120 degrees outside of storage section 21A and communicate with storage section 21A. Support shaft M1, bearing E1, and shaft adapter D1 are arranged in hollow section Q1, support shaft M2, bearing E2, and shaft adapter D2 are arranged in hollow section Q2, and support shaft M3, bearing E3, and shaft adapter D3 are arranged in hollow section Q3. Bearings E1 to E3 and shaft adapters D1 to D3 can be placed in these hollow sections Q1 to Q3 through opening 21B and storage section 21A.

Openings K1 to K3 are formed on the outer surface of case 21 at angular intervals of 120 degrees, and communicate with hollow portions Q1 to Q3, respectively. Support shafts M1 to M3 can be placed in storage portion 21A by inserting them into openings K1 to K3, respectively.

The inner lid 23 is fixed to the case 21 by a plurality of bolts J7. Furthermore, an outer lid 22 that covers the inner lid 23 is fixed to the inner lid 23. The material of the inner lid 23 is, for example, duralumin, and the material of the outer lid 22 is, for example, resin.

The inner lid 23 has multiple through holes 23A formed in it. The lower ends of the lift guides T1 to T3 (see Figures 13 and 14) are inserted into the through holes 23A of the inner lid 23, respectively, and protrude to the outside of the inner lid 23. On the outside of the inner lid 23, nuts S1 to S3 are attached to the lower ends of the lift guides T1 to T3. This allows the base 13 to be positioned within the storage section 21A of the case 21.

When the pitch angle change motor 5A rotates under the above configuration, the gears G3 and G2 in the rotation transmission section 6A transmit the rotational motion of the pitch angle change motor 5A to the gear G1 (see Figures 8 to 11). Since the gear G1 is fixed to the ball screw shaft 7F of the rotary-linear conversion section 7, the rotational motion of the pitch angle change motor 5A is transmitted to the ball screw shaft 7F. When the ball screw shaft 7F rotates, the ball screw nut 7G and the linear transmission shaft 7D are guided by the linear guide section 7E and move linearly in the vertical direction (see Figures 9 to 11).

The linear motion of the linear transmission shaft 7D is transmitted to the linear body 11. In response to the linear motion of the linear transmission shaft 7D, the racks A1 to A3 fixed to the linear body 11 move linearly in the vertical direction together with the linear body 11. When the racks A1 to A3 move linearly together with the linear body 11, the lift guides T1 to T3 guide the linear body 11 (see Figures 13 and 14). The range of movement of the linear body 11 is limited by the base 13 and nuts S1 to S3. The racks A1 to A3 are engaged with pinions B1 to B3, respectively, and when the racks A1 to A3 move linearly, the pinions B1 to B3 fixed to the support shafts M1 to M3 rotate at the same time (see Figures 4 and 5). Therefore, in response to the rotational motion of the pinions B1 to B3, the support shafts M1 to M3 rotate around their respective axes. Grips P1 to P3 that support the rotors H1 to H3 are attached to the support shafts M1 to M3, and the rotational motion of the support shafts M1 to M3 is transmitted to the rotors H1 to H3. Therefore, the pitch angles of the rotors H1 to H3 are changed at the same time. For example, when the linear body 11 is in the position shown in FIG. 13, the pitch angles of the rotors H1 to H3 are set as shown in FIG. 2, and when the linear body 11 is in the position shown in FIG. 14, the pitch angles of the rotors H1 to H3 are set as shown in FIG. 3.

The thrust generating device 1 can change the thrust given to the flying object by changing the rotation angle of the pitch angle changing motor 5A and therefore the pitch angle of the rotors H1 to H3. By changing the thrust by changing the pitch angle, the response speed of the thrust change can be increased and the stability of the flying object can be improved compared to a method of changing the thrust by changing the rotation speed of the thrust generating motor 2. In addition, since the thrust given to the flying object can be changed by changing the pitch angle of the rotors H1 to H3, there is no need to enlarge the rotors H1 to H3, and there is no need to excessively increase the rotation speed of the thrust generating motor 2. Since there is no need to enlarge the rotors H1 to H3, it is possible to suppress the size and weight of the flying object. In addition, since the increase in the rotation speed of the thrust generating motor 2 is suppressed, noise dependent on the rotation speed can be suppressed.

In addition, in the thrust generating device 1, the pitch angle of the rotors H1 to H3 can be changed electrically, eliminating the need to use hydraulics. This eliminates the need to provide a hydraulic control unit that controls the supply and discharge of oil, and a complex rotary seal mechanism for oil sealing the rotor, making it possible to prevent the thrust generating device 1 from becoming too large, and also facilitating the maintenance and repair of the thrust generating device 1.

In this embodiment, by using a rack and pinion as the motion conversion mechanism of the linear motion rotation conversion unit 8, it is possible to align the longitudinal direction of each of the racks A1 to A3 with the linear motion direction of the linear moving body 11, and it is possible to align each of the pinions B1 to B3 concentrically with the support shaft. Therefore, the arrangement of the three racks and pinions can be made compact, and it is possible to house the linear motion rotation conversion unit 8 within the hub 10 while preventing the hub 10 from becoming larger.

The structure in which the grips P1-P3, which support the rotors H1-H3, are supported by the hub 10 will be described in more detail below.

Figure 18 is an enlarged cross-sectional view of a portion of the hub 10 that supports the grip P1. Figure 19 is a cross-sectional view of the grip P1 and its surroundings. Figure 20 is an exploded perspective view of the components shown in Figure 19. Figure 21 is a front view of the assembled components shown in Figure 19.

As shown in FIG. 18, the case 21 of the hub 10 houses the linear motion transmission shaft 7D and the motion conversion mechanism of the linear motion rotation conversion unit 8 that converts the linear motion of the linear motion transmission shaft 7D into the rotational motion of the multiple grips P1-P3 (particularly the linear body 11, racks A1-A3, and pinions B1-B3). The case 21 further houses the support shafts M1-M3 and the bearings E1-E3 that rotatably support the support shafts M1-M3. The support shafts M1-M3 can be considered to be the inner ends of the grips P1-P3, respectively.

The hub 10 can be disassembled into the case 21, outer lid 22, and inner lid 23, but the case 21 itself cannot be separated. In other words, the case 21 is an integrally formed, non-separable case. The case 21 has multiple openings K1-K3 into which the support shafts M1-M3, which are the inner ends of the grips P1-P3, can be inserted with the outer ends of the grips P1-P3 positioned outside the case 21.

Below, the mechanism supporting grip P1 and rotor H1 will be described in detail, but the mechanisms supporting the other grips P2, P3 and rotors H2-H3 are similar (grips P1-P3 are the same type, with the same shape and size).

As shown in Figures 18 to 21, a rubber ring 30, a thrust washer 31, a needle-shaped thrust bearing 32, a thrust washer 33, a shaft adapter D1, a bearing E1, a pinion B1, a C-shaped retaining ring 34, and a fastening ring 35 are arranged around the support shaft M1.

The support shaft M1 is inserted into the rubber ring 30. As shown in FIG. 18, the rubber ring 30 is interposed between the outer surface of the outer end wall Q1a of the hollow portion Q1 of the case 21 and the outer end of the grip P1, closing the opening K1 and preventing the bearing grease from scattering while suppressing the intrusion of dust into the inside of the case 21. The grip P1 including the support shaft M1 is rotatable relative to the rubber ring 30.

Thrust washers 31 and 33 are in contact with both end faces of needle-shaped thrust bearing 32. Thrust washers 31 and 33 are raceways, or rings, and are in contact with the multiple needles of needle-shaped thrust bearing 32. A support shaft M1 is inserted into thrust washer 31, needle-shaped thrust bearing 32, and thrust washer 33. Support shaft M1 does not contact the inner circumferential surfaces of thrust washer 31, needle-shaped thrust bearing 32, and thrust washer 33, and grip P1 including support shaft M1 can rotate relative to them.

A support shaft M1 is inserted into the shaft adapter (cylinder) D1, and the shaft adapter D1 is rotatably inserted into a bearing E1. The bearing E1 is, for example, a radial bearing, preferably a double row angular contact ball bearing. The shaft adapter D1 can be divided at a plane including the longitudinal axes of the grips P1 to P3, and has two segments D1a and D1b (see FIG. 20).
(See FIG. 1). The segments D1a and D1b are combined to form a shaft adapter D1, which is a stepped cylinder.

The shaft adapter D1, which is composed of segments D1a and D1b, has a sleeve 40 and a flange 41. The flange 41 is disposed radially outward of the hub 10 from the sleeve 40. The sleeve 40 is inserted into the inner ring of the bearing E1. The end face of the bearing E1 faces the flange 41.

A fastening ring 35 is wound around the flange 41 of the shaft adapter D1. The fastening ring 35 is a ring with ends, and uses elastic restoring force to restrain the flange 41 and prevent the combined segments D1a and D1b from separating.

The end M1a of the support shaft M1 is formed in a substantially elliptical cylindrical shape and is inserted into the substantially elliptical cylindrical central hole of the pinion B1. Therefore, the pinion B1 does not rotate with respect to the support shaft M1. A groove M1b is formed in the end M1a of the support shaft M1, and a C-shaped retaining ring 34 is fitted into the groove M1b. The C-shaped retaining ring 34 restricts the axial movement of the pinion B1 and fixes the pinion B1 to the end M1a of the support shaft M1.

Inside the case 21, the bearings E1 to E3 are positioned radially outward of the hub 10 relative to the linear body 11, racks A1 to A3, and pinions B1 to B3, and the needle thrust bearing 32 is positioned radially outward of the hub 10 relative to the bearings E1 to E3.

The outer end of the grip P1 is bifurcated and has two parallel flat plate sections. Although not shown, the base of the rotor H1 is sandwiched between these flat plate sections. These flat plate sections have multiple through holes, and the base of the rotor H1 is fixed to the outer end of the grip P1 by bolts 36 that pass through the through holes and nuts 37 that engage with the bolts 36. Countersunk holes are formed around the through holes of the flat plate sections, and washers 38 are placed in these countersunk holes. Bolts 36 are inserted into the washers 38.

17 and 18, the hollow portion Q1 of the case 21 has a small diameter hole portion Q1b and a large diameter hole portion Q1c. The small diameter hole portion Q1b and the large diameter hole portion Q1c are coaxial circular holes, and the small diameter hole portion Q1b located on the radially outer side of the hub 10 has a smaller inner diameter than the large diameter hole portion Q1c located on the radially inner side of the hub 10. A step wall Q1d is provided between the small diameter hole portion Q1b and the large diameter hole portion Q1c. Furthermore, the opening K1, the small diameter hole portion Q1b, and the large diameter hole portion Q1c are coaxial circular holes, and the inner diameter of the opening K1 is smaller than the inner diameter of the small diameter hole portion Q1b.
Furthermore, as shown in Fig. 17, among the side walls of the case 21, the opposing wall Q1e that faces the opening K1 has no holes. Similarly, as shown in Fig. 15, the opposing wall Q2e that faces the opening K2 and the opposing wall Q3e that faces the opening K3 have no holes. In this embodiment, the side walls of the case 21 have no holes other than those of the openings K1 to K3.

The thrust washer 31, needle-shaped thrust bearing 32, and thrust washer 33 are disposed in the small diameter hole Q1b of the hollow portion Q1 of the case 21, and the thrust washer 31 is brought into contact with the inner surface of the outer end wall Q1a of the hollow portion Q1. The flange 41 of the shaft adapter D1 is brought into contact with the thrust washer 33 on the opposite side. The fastening ring 35 and flange 41 are also disposed in the small diameter hole Q1b.

The outer diameter of the outer ring of the bearing E1 is larger than the outer diameter of the needle thrust bearing 32. The bearing E1, into which the sleeve 40 of the shaft adapter D1 is inserted, is disposed in the large diameter hole portion Q1c of the hollow portion Q1 of the case 21, and an end face of the outer ring of the bearing E1 is brought into contact with a step wall Q1d of the hollow portion Q1. The other end face of the inner ring of the bearing E1 is brought into contact with an end face of the pinion B1 fixed to the end portion M1a of the support shaft M1.

Therefore, in the axial direction of the support shaft M1, the thrust washer 31, the needle-shaped thrust bearing 32, the thrust washer 33 and the shaft adapter D1 are sandwiched between the pinion B1 and the inner surface of the outer end wall Q1a of the hollow portion Q1 of the case 21. Also, in the axial direction of the support shaft M1, the bearing E1 is sandwiched between the pinion B1 and the step wall Q1d of the hollow portion Q1 of the case 21.

In the shaft adapter D1, the inner circumferential surface of the sleeve 40 has a smaller diameter toward the radial outside of the hub 10. On the other hand, in the outer circumferential surface of the support shaft M1, the portion M1c that is inserted into the shaft adapter D1 has a smaller diameter toward the radial outside of the hub 10.

Therefore, when the grip P1 is pulled radially outward of the hub 10 by the centrifugal force acting on the rotor H1, the portion M1c of the outer peripheral surface of the support shaft M1 fits onto the inner peripheral surface of the sleeve 40 of the shaft adapter D1. In this way, when centrifugal force is applied to the sleeve 40 of the shaft adapter D1, the flange 41 of the shaft adapter D1 transmits the centrifugal force to the needle-shaped thrust bearing 32 (as a thrust force to the needle-shaped thrust bearing 32). When centrifugal force is applied to the needle-shaped thrust bearing 32, the thrust washer 31 comes into contact with the inner surface of the outer end wall Q1a of the case 21, and the needle-shaped thrust bearing 32 is supported by the inner surface of the outer end wall Q1a of the case 21. In this way, the centrifugal force acting on the grip P1 is applied to the needle-shaped thrust bearing 32 when the rotor H1 rotates.

When centrifugal force is applied to the shaft adapter D1, the flange 41 of the shaft adapter D1 transmits the centrifugal force to the needle-shaped thrust bearing 32, and the needle-shaped thrust bearing 32 is supported on the inner surface of the outer end wall Q1a of the case 21, so that the shaft adapter D1 functions as a retainer for the grips P1 to P3 subjected to the centrifugal force.
In other words, because the support shaft M1 has a tapered shape, when the grip P1 is pulled radially outward of the hub 10 by the centrifugal force acting on the rotor H1, a force is applied in a direction that pushes the shaft adapter D1 apart. At this time, the inner ring of the bearing E1 limits the direction in which the shaft adapter D1 can expand, so a wedge effect is generated between the support shaft M1 and the shaft adapter D1. When the centrifugal force increases, this wedge effect also increases, making it more difficult for the support shaft M1 to come out of the case 21.
As described above, the step wall Q1d is provided between the small diameter hole Q1b and the large diameter hole Q1c in the hollow portion Q1 of the case 21, the bearing E1 is disposed in the large diameter hole Q1c, and the end face of the outer ring of the bearing E1 is brought into contact with the step wall Q1d of the hollow portion Q1. Therefore, the centrifugal force is also received by the step wall Q1d.

In addition, when the centrifugal force increases to a certain extent, the portion M1c of the outer peripheral surface of the support shaft M1 fits into the inner peripheral surface of the sleeve 40 of the shaft adapter D1, so that the longitudinal axis of the grip P1 is adjusted to the ideal direction.

In this embodiment, in each hollow portion Q1 of the case 21, double row angular contact ball bearings E1 to E3 that rotatably support the grips P1 to P3 are disposed in the large diameter hole portion Q1c, and a needle thrust bearing 32 is disposed in the small diameter hole portion Q1b. Therefore, the thrust generating device 1 can be made smaller than when structures are provided that individually support the double row angular contact ball bearings E1 to E3 and the needle thrust bearing 32.

In this embodiment, the grip including the support shaft can be changed according to the type of rotor. Fig. 22 is a cross-sectional view of a grip P4 of another type different from the grips P1 to P3 and its vicinity. Fig. 23 is an exploded perspective view of the components shown in Fig. 22.

The outer end of grip P4, which is located on the outside of case 21, is larger than the outer end of grip P1 and is suitable for supporting a rotor (not shown) that is larger and heavier than rotors H1 to H3. Therefore, once an appropriate rotor is selected according to the weight of the flying object to which the thrust generating device is attached, and thus the thrust required for the thrust generating device, a grip suitable for that rotor can be attached to hub 10.

The outer end of the grip P4 is bifurcated and has two parallel flat plate sections. Although not shown, the base of the rotor is sandwiched between these flat plate sections. These flat plate sections have multiple through holes, and the base of the rotor is fixed to the outer end of the grip P4 by bolts 36a that pass through the through holes and nuts 37a that engage with the bolts 36a.

On the other hand, the support shaft M1, which is the inner end of the grip P4, has the same shape and size as the support shaft M1 of the grip P1. Therefore, the grip including the support shaft can be changed according to the type of rotor while the linear body 11, racks A1-A3, pinions B1-B3, bearings E1-E3, and other components remain on the hub 10. While the grip can be changed, the radial bearings E1-E3 and the complex linear body 11, racks A1-A3, pinions B1-B3, and other components can be used without modification, minimizing increases in manufacturing costs.

In this embodiment, the support shaft, which is the inner end of the grip, is inserted, and each shaft adapter inserted into the radial bearing can be divided with a plane including the longitudinal axis of the grip as a boundary. When the grip is assembled into the hub 10, the support shafts M1 to M3 are inserted through the openings K1 to K3 of the case 21 and arranged inside the case 21. Inside the case 21, the bearings E1 to E3 are arranged around the support shafts M1 to M3 so as to rotatably support the grips P1 to P3. Specifically, the support shafts M1 to M3 are inserted into the shaft adapters D1 to D3, and the shaft adapters D1 to D3 are inserted into the bearings E1 to E3. Each of the shaft adapters D1 to D3 can be divided with a plane including the longitudinal axis of the grips P1 to P3 as a boundary, and can be easily arranged around the support shafts M1 to M3 and easily inserted into the bearings E1 to E3 in a combined state. Therefore, even if the case 21 is a non-split type case that cannot be split, it is possible to easily place the bearings E1 to E3 around the support shafts M1 to M3 inside the case 21. This makes it easy to change the grips P1 to P3.

A method for manufacturing the case 21 will be described below with reference to FIG.
As described above, the case 21 is an integrally formed, non-split type case. The case 21 can be manufactured by machining.
First, prepare a base material for the case 21. The base material for the case 21 is, for example, duralumin. Then, the base material for the case 21 is set in a processing machine, and the case 21 is formed by cutting it out using a cutting tool.

Specifically, first, a cutting tool is applied from the outside of the base material to a pair of opposing surfaces (top and bottom surfaces) of the base material of case 21 to form openings 21B and 21C. This forms storage section 21A penetrating the top and bottom surfaces. Next, a cutting tool is applied from the outside of the base material to the side surfaces of case 21 to form openings K1 to K3.
Next, a cutting tool is applied obliquely to the axial direction of the housing portion 21A from the openings (openings 21B and 21C) at both axial ends of the housing portion 21A to form hollow portions Q1 to Q3 outside the housing portion 21A and communicating with the housing portion 21A. At this time, the cutting tool is inserted in the directions of the arrows α and β shown in FIG.
In this manner, by inserting a cutting tool obliquely through openings 21B, 21C formed on the top and bottom surfaces of case 21 and performing cutting processing, hollow portions Q1-Q3 having an inner diameter larger than that of openings K1-K3 are formed inside openings K1-K3.

As described above, in this embodiment, the case 21 that houses the linear body 11, the racks A1 to A3, the support shafts M1 to M3, the bearings E1 to E3, the shaft adapters D1 to D3, and the pinions B1 to B3 is an integrally formed non-split type case. This case 21 can be formed integrally by machining.
In this way, the case 21 is not a split case having a structure in which, for example, the case is split into two parts, upper and lower, and the support shafts M1 to M3 are sandwiched between them and secured by bolts or the like. By making the case 21 a non-split case as in this embodiment, it is possible to increase the strength compared to a split case. In addition, since no fastening parts are required, it is possible to reduce the weight accordingly.

Furthermore, in this embodiment, no holes other than the openings K1 to K3 are provided in the side wall of the case 21. In other words, no processing holes are provided in the surfaces facing the openings K1 to K3.
When forming the case 21 by machining, which has hollow portions Q1-Q3 located inside the openings K1-K3 and larger in diameter than the openings K1-K3, holes for machining are generally provided at positions facing the openings K1-K3, and a cutting tool is inserted through the holes for machining to form the hollow portions Q1-Q3. However, when holes for machining are provided, it is necessary to give the case 21 a thickness in order to ensure strength, which increases the weight. In contrast, in this embodiment, no holes for machining are provided on the side surfaces of the case 21, so a lightweight structure can be maintained.

In this way, the case 21 is an integrally formed, non-split case with no holes in the side walls except for the openings K1 to K3, making it possible to reduce weight while maintaining strength.

Although the present invention has been shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that changes in form and detail may be made therein without departing from the scope of the invention as set forth in the appended claims. Such changes, modifications and alterations are intended to be within the scope of the present invention.

For example, in the above embodiment, the propeller R is disposed directly below the thrust generating device 1, and the thrust generating device 1 is attached to the bottom of the airframe, but the propeller R may be disposed directly above the thrust generating device 1, and the thrust generating device 1 may be attached to the top of the airframe.

Reference Signs List 1... thrust generating device, 2... thrust generating motor, R... propeller, H1 to H3... rotor blades, P1 to P3... grips, M1 to M3... support shaft, 4... rotor shaft, 5A... pitch angle changing motor, 6... motion transmission unit, 6A... rotation transmission section, 7... rotation-to-linear conversion section, 7D... linear transmission shaft, 7E... linear guide section, 7F... ball screw shaft, 7G... ball screw nut, 8... linear rotation conversion section, 10... hub, 11 ...linear body, A1 to A3...rack, B1 to B3...pinion, D1 to D3...shaft adapter, D1a...segment, D1b...segment, 40...sleeve, 41...flange, E1 to E3...bearing, 21...case, 21A...accommodation portion, 21B...opening, 21C...opening, K1 to K3...opening, Q1 to Q3...hollow portion, Q1a...outer end wall, Q1e to Q3e...opposing wall, 32...needle thrust bearing

Claims (1)

A method for manufacturing a non-split type case provided in a thrust generating device, comprising the steps of:
The thrust generating device comprises:
a thrust generating motor that rotates a plurality of rotors to generate thrust;
a pitch angle changing motor for changing the pitch angle of the rotor;
a rotation transmission unit connected to the pitch angle changing motor;
a first motion conversion unit having a linear motion shaft and a first motion conversion mechanism, the first motion conversion mechanism being connectable to the rotation transmission unit and the linear motion shaft and converting rotation of the rotation transmission unit into linear motion of the linear motion shaft;
a second motion conversion unit that converts the linear motion of the linear motion shaft into rotational motion to change the pitch angle of the rotor,
The second motion conversion unit includes:
a hub rotated by the thrust generating motor;
A plurality of grips attached to the hub and each supporting the rotor blade;
a second motion conversion mechanism that converts the linear motion of the linear motion shaft into a rotational motion of the plurality of grips;
a plurality of radial bearings each rotatably supporting an inner end of the grip;
the hub has an integrally formed, non-split case that houses the inner ends of the grips, the second motion conversion mechanism, and the radial bearings;
The method for manufacturing the non-split type case includes the steps of:
providing a base material for the non-split type case;
forming the non-split type case by machining from the base material;
The step of forming the non-split type case includes:
forming a housing portion penetrating a pair of opposing surfaces of the base material and housing the second motion conversion mechanism;
and applying a cutting tool to openings at both axial ends of the accommodating portion at an angle to the axial direction of the accommodating portion to form a hollow portion in which the multiple radial bearings are disposed, the hollow portion being outside the accommodating portion and communicating with the accommodating portion.

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